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Centralized versus decentralized water and sanitation in Northern Frogn, Norway

THT282 2012 - Case Frogn. Centralized versus decentralized water and sanitation in Northern Frogn, Norway.

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Centralized versus decentralized water and sanitation in Northern Frogn, Norway

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  1. THT282 2012 - Case Frogn Centralized versus decentralized water and sanitation in Northern Frogn, Norway A centralized (1) water supply and wastewater system has been planned for the northern part of Frogn municipality. The pictures on the following slides give you an idea about the geography of the area. The area consists of 117 houses and 289 cabins all in a rural setting. All homes/cabins currently have onsite or decentralized systems for water and sanitation, but many treatment systems especially are very simple and do not fulfill the current requirements of the municipality (90% removal of BOD and P and 40% removal of nitrogen, when the discharge is close to beaches or to sensitive streams the effluent should also meet swimming water quality). The new centralized alternative is expensive and a fee of at least 100 000 NOK is anticipated for hooking up to the system. In addition homeowners have to pay the work on their own property. This work range from 25 000 to 100 000 NOK depending on the distance to the main sewer and whether or not pumping is needed (sewer higher than the property). Due to strong opposition from local stakeholders the municipal council has required that a decentralized alternative must be presented. In this case you are going to make an assessment of the decentralized alternative and compare it to the centralized option. For questions and stakeholders views you can call: Are Dammann on 66960336

  2. Where is Northern Frogn? Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES 2 Photo: Ronny Hansen The A indicates the area where your case is based, Oslo is the capital of Norway www.umb.no

  3. Where is Northern Frogn? The blue line indicates the area where your case is based Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES Hasla stream Dal stream 3 Photo: Ronny Hansen www.umb.no

  4. Where is Northern Frogn? You can use Google Maps And the website given below to familiarize yourself with the area. Google maps also allows for satelite images. Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES 4 Photo: Ronny Hansen http://www.panoramio.com/photo/4607779 www.umb.no

  5. Pollution of surface water from onsite systems in Blylagsdammen, Nordre Frogn Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES Blylagsdammen is an old dam where they produced ice for export to England. The dam is bordering the Northern Frogn area. The dam is surrounded by houses that pollute the dam. A narrow wildlife protection area circumfences the dam (see map). 5 Blylagsdammen nature conservation area www.umb.no

  6. Pictures from Blylaget Blylagsdammen Frogn Municipality Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES 6 www.umb.no

  7. Pictures from Northern Frogn The soil cover can be thin and dispersed Frgn Municipality Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES 7 Hasla stream Photo: Ronny Hansen www.umb.no

  8. Pictures from Northern Frogn Blylaget Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES 8 www.umb.no

  9. Pictures from Northern Frogn Solbukta - ”The sun bay” Department of Plant and Environmental Sciences NORWEGIAN UNIVERSITY OF LIFE SCIENCES 9 www.umb.no

  10. Pictures from Northern Frogn Skating on Bunnefjorden Department of Plant and Environmental Sciences Northern Frogn NORWEGIAN UNIVERSITY OF LIFE SCIENCES Oslo 10 www.umb.no

  11. THT282 2012 - Case Frogn • Based on the background information you should decide if you think it is possible to • use the existing water supply (2) and what are the pro´s and con´s of a • decentralized water supply system as compared to a centralized system? • Here are some key issues that you have to consider: • Is the existing water supply system adequate in terms of providing sufficient water • of good quality? • What upgrade, if any, would you suggest for the existing water supply system ? • What are the main sources of pollution that might influence a local groundwater supply • in this case? • Is the groundwater safe if you centralize and pipe all the sewage out of the area? • Try to also identify other key questions that you need to resolve • You should also look into the existing wastewater situation (3) and judge what • kind of local systems that you would recommend for wastewater treatment • in the area for the decentralized option. • Your work should include an assessment of the decentralized option and compare • advantages and disadvantages of the centralized and decentralized options regarding • water pollution (4), health and hygiene, preferences of the citizens/stakeholders, • economy as well as operation and maintenance. Use the information and links given • in this ppt file. • You are welcome to call Are Damann 66960336 for a stakeholder view.

  12. THT282 2012 - Case Frogn Centralized versus decentralized water and sanitation in Northern Frogn municipality, Norway In this exercise you should gain an overview of the most common decentralized treatment systems; natural treatment systems, source separating systems and package treatment plants (an overview of the decentralized systems is given in slide 14). You are not required to know how to size the systems, but you should be able to suggest where the different decentralized options can be used considering the natural conditions in Frogn. You should also have a general knowledge of what a conventional centralized systems offer in terms of treatment and transport systems for water and sewerage. In the following slides of this presentation you will be introduced to different treatment systems. You will also find useful information elsewhere in the SSWM toolbox and under the icons attached to the opening page of this exeercise. If you cannot find the answers in the documents and material attached to this exercise or need assistance feel free to contact Petter or Manoj by email: petter.jenssen@umb.no, manoj.pandey@umb.no Your work should be presented in a short ppt file with a comprehensive text comments so it can be understood form the ppt presentation alone. You should be prepared to present the work in class.

  13. THT282 2012 - Case Frogn Maps can display very useful information regarding planning of water and sanitary systems. They can show the topography, the location of dwellings and other man made infrastructure as well as water courses and soil and geological information. A compilation of maps and studying their information is often crucial for a consultant and can save many hours of field survey. However, you should be aware of that maps always provide a simplification of reality and that some infomation can only be collected by field work. In this case you to use maps and internet and other information available in print, but those that have the time and interest can take a tour of the area since it is only 15 – 20 km from our campus. To the right in this slide is a map of the whole Frogn municipality. The area of interest is to the north-east and marked with red lines. The location of the existing sewage treatment plant is shown You can view both hydrogeological information, bedrock, soils (Quarternary maps) as well as maps presenting infiltration possibilities on:www.ngu.no/en-gb/hm/Maps-and-data/Maps-and-services/ Quarternary maps display soils by their genetic origin and since Norway was covered by ice 10 000 years ago soils are young and most soils have ben generated due to glacial action (eg. tills). Knowing a little bit about the properties of diffrent soils the quarternary maps give you an idea about the soil suitability for using infiltration systems. Traditional infiltration systems (5) needs well drained soils of depths of at least one meter above exsisting groundwater. Thin tills and marine deposits are in general not suited. The Norwegian Geological Survey (NGU) has made maps derived form quarternary maps that show the suitability for infiltration of wastewater. A topographic and simple soils map can be viewed/downloaded from: http://kart.follokart.no The area of concern Sewage treatment plant

  14. THT282 2012 - Case Frogn Some decentralized wastewater treatment options Package treatment (25, 12, 13) Source separating Systems (14,15,16,17) Biofilters/ aerobic Treatment (6, 26) Ponds (7, 19) Soil infiltration Systems (5, 8, 9, 20, 21) Constructed wetlands (6, 22, 23, 10)

  15. THT282 2012 - Case Frogn Natural systems: Soil infiltration, Constructed wetlands and Ponds Natural systems as soil infiltration (5), constructed wetlands (6) and ponds (19 page 1-9) are alternatives to the more technical conventional treatment systems. Ponds are generally not considered as an alternative for single home systems in Frogn due to the fencing requirements needed for such systems in Norway and due to variable performance in the winter. However, ponds in combination with subsurface flow constructed wetlands can perform very well in Norway (7). The natural systems require more area than conventional systems. Constructed wetlands and ponds can be built almost regardles of the soil and hydrogiological conditions at a given site. Infiltration systems use the groundwater as the final reciving body for the treated water. It is therefore necessary to have suitable soil conditions in order to use an infiltration type system. It is also very important to make sure that the nearby wells are not polluted by the infiltration systems.

  16. THT282 2012 - Case Frogn Natural systems: Soil infiltration, Constructed wetlands and Ponds • Natural systems are mainly small onsite systems for one ore more dwellings/cabins, but if the natural conditions are favorable larger systems can be built. The largest natural system in Norway in an infiltration system in Rena that serves 8000 people (20). The treatment system at Rena is one of the stops on the excursion October 15th. In Arizona, USA an infiltration system for • 80 000 people is reported. • Soil infiltration systems are the most common onsite systems in Norway (5) Mound systems (8) and intermittent sandfilters (9) are in principle an infiltration system, but sandfilters can be built regardless of soil conditions as long as it is possible to excavate a trench for the sand. Sandfilters are a common system used by dwellings in the area (3). You can read more about soil infiltration systems in (21) Further reading about the functio and design of constructed wetlands are given in (10, 22, 23) or ponds (19). You can watch an animation of elucidating the the function of a cold climate constructed wetland (24).

  17. THT282 2012 - Case Frogn Decentralized conventional treatment:Compact filter systems and Package treatment systems If the soils do not allow the use of infiltration into the natural soils and the space does not allow a constructed wetland or a sandfilter there are several compact systems available. A downscaled wetland system with very high performance is described in (26) Package treatment system (12) are downscaled conventional treatment systems. Many such systems are available on the Norwegian market (25).Package treatment systems are technically more complex than natural systems, and need more maintenance, but the maintenance need for most systems is only 2 – 4 times per year. In order to remove phosphorus the package treatment systems use chemicals mostly aluminum or iron salts. Despite the use of chemicals many package treatment systems do not meet the Norwegian requirement of 1ppm in the effluent. An assessment of the performance of package treatment systems in Norway is given in (13, in Norwegian).

  18. THT282 2012 - Case Frogn Systems with source separation The majority of the cabins and many permanent homes in the area are using some kind of source separating system today (3). An extensive overview of source separating systems is given in (14). If you are interested in urine diverting systems specifically you can read (15). The vacuum systems can be studied on the following website: www.jetsgroup.com/no/ Examples of source separating systems in Norway are given in (16) and (17). You can watch a video showing the function of a small (one house/cabin) greywater package treatment plant http://standard.jetsgroup.com/no/Products/Greywater-treatment-plant.aspx

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